热送热装技术可以显著降低加热炉能源消耗、提高生产效率、减少钢-轧界面的碳排放。然而,热送热装的微合金钢板坯在轧制后极易产生红送裂纹,限制了该技术的应用。为了研究300 mm厚微合金钢板坯的扇形段热装预处理工艺,采用高温拉伸试验研究了热装预处理过程的合理冷却速度,通过工业试验研究了热装预处理过程板坯表面温度和微观组织的变化规律,利用统计的方法研究了热装预处理后钢板的表面质量和力学性能。结果表明,热装预处理过程合理的冷却速度应在4.0 ℃/s以上。在扇形段热装预处理过程板坯表面温度由920 ℃降至387 ℃,冷却速度约4.2 ℃/s,表面回温可达742 ℃,回温速度约1.2 ℃/s;通过快冷和回温使得板坯表面形成了细小的贝氏体组织。热装预处理工艺实施后,热装温度由500~550 ℃提高至600~650 ℃,消除了高温热送热装带来的红送裂纹问题,钢板力学性能稳定。
Abstract
Hot delivery and hot charging technology can significantly reduce energy consumption of heating furnaces, improve production efficiency, and reduce carbon emissions during steelmaking and rolling process. However, hot delivery cracks are easily existed on the plate surface after high temperature hot delivery of microalloyed steel slabs, which limits the application of this technology. In this work, the high temperature tensile test experiment was carried out to investigate the reasonable cooling rate during the hot charging pretreatment process of 300 mm slab. The variation process of surface temperature and microstructure of slab during the hot charging pretreatment process was studied through industrial experiments. The surface quality and mechanical properties of steel plates with hot charging pretreatment process were studied using statistical methods. The results indicate that the surface temperature of 300 mm thick slab is deceased from 920 ℃ to 387 ℃, and the cooling rate is about 4.2 ℃/s during the segment hot charging pretreatment process. The surface temperature is return to 742 ℃, and the heating rate is about 1.2 ℃/s. Fine bainite structures are formed through rapid cooling and reheating on the surface of the slab. After the implementation of the hot charging pre-treatment process, the hot charging temperature of the slab is increased from 500-550 ℃ to 600-650 ℃, and the hot delivery cracks are eliminated, and the mechanical properties of the steel plate are stable.
关键词
热装热送 /
红送裂纹 /
热装预处理 /
连铸 /
厚规格板坯
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Key words
hot charging and delivery /
hot delivery cracks /
hot charging pretreatment /
continuous casting /
thick slab
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